CD19-specific CTL clone, but not CD20-specific CTL-clone, lyses CD19⁺ B-ALL and lymphoma targets.

CD19-specific effector cells from a CD8⁺ CTL clone and a CD19-specific CD4⁺ CTL clone (left insert ) and CD20-specific effector cells from a CD8⁺ CTL clone (right insert) were incubated with some or all of ⁵¹Cr-labeled CD19⁺ B-ALL and lymphoma lines: Daudi (○), SUP-B15 (⋄), JM1 (▵), RS4 (■), and CD19⁻target line K562 (×). Daudi cells, but not JM1 and K562 cells, express CD20 determinant. Lytic activity was calculated by measuring chromium release after 4 hours. Spontaneous release for each target was 10% or less. Average counts ± SD from triplicates are shown.